Nephronophthisis is a disorder that affects the kidneys. It is characterized by inflammation and scarring (fibrosis) that impairs kidney function. These abnormalities lead to increased urine production (polyuria), excessive thirst (polydipsia), general weakness, and extreme tiredness (fatigue). In addition, affected individuals develop fluid-filled cysts in the kidneys, usually in an area known as the corticomedullary region. Another feature of nephronophthisis is a shortage of red blood cells, a condition known as anemia.
Nephronophthisis has several genetic causes, which are used to split the condition into distinct types. Nephronophthisis type 1, which is the most common type of the disorder and one cause of juvenile nephronophthisis, results from changes affecting the NPHP1 gene. The proteins produced from NPHP1 and the other genes involved in nephronophthisis are known or suspected to play roles in cell structures called cilia. Cilia are microscopic, finger-like projections that stick out from the surface of cells and are involved in chemical signaling. Cilia are important for the structure and function of many types of cells and tissues, including cells in the kidneys, liver, brain, and the light-sensitive tissue at the back of the eye (the retina).
Nephronophthisis is found in populations worldwide. It occurs in an estimated 1 in 50,000 newborns in Canada, 1 in 100,000 in Finland, and 1 in 922,000 in the United States. Its incidence in other populations is unknown. Nephronophthisis is the most common genetic cause of ESRD in children and young adults.
This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.
Published Date: September 01, 2014Published By: National Institutes of Health